摘要
将水-气等价为一种均匀的流体,可以采用两相孔隙介质理论来模拟准饱和土,基于Bardet根据Biot饱和多孔连续介质的波动方程提出的准饱和土的波动方程,建立了半空间表面透水和不透水两种情况下准饱和土体中瑞利波的频率特征方程,绘制了不同饱和度的瑞利波速与剪切波速的比值及瑞利波速的实部随无量纲频率的变化曲线,固体土骨架和孔隙流体的归一化竖向位移和水平位移(准饱和土体某一深度的位移与饱和土体表面处的位移的比值)随归一化深度(深度与瑞利波波长的比值)的变化曲线,通过比较这些曲线发现饱和度对准饱和土体瑞利波的传播特性的影响很明显,瑞利波速与剪切波速的比值及瑞利波速的实部随着饱和度的增大而增大,而归一化位移则随着饱和度的增大而减小,但饱和度从95%增大到99%时它们增大或减小的幅值要小于饱和度从99%增大到100%时的情况,这为瑞利波的传播规律研究和现场测试与数据分析提供了理论依据。
Water and gas are considered as a homogeneous fluid and so nearly saturated soils can be simulated by theory of two-phase pore media.Based on the wave motion equation of nearly saturated soils obtained by Bardet according to the Biot's wave motion of saturated soil,the frequency characteristic equations of Rayleigh waves in a half-space of nearly saturated soils whether or not its surface is permeable to water are established.Some curves are drawn,such as,the curves of the ratio of the Rayleigh wave velocity to that of the shear wave and the real part of Rayleigh wave velocity versus normalized frequencies,and the curves of the normalized vertical and horizontal displacements of the soil skeleton and the fluid,the ratios of displacements in a certain depth of the nearly saturated soils to those of the saturated soils surface versus the normalized depth,i.e.,the ratio of the depth to Rayleigh wave length.By analyzing these curves,some important conclusions are obtained that the saturation degree has important influences on the propagation characteristics of the Rayleigh wave in nearly saturated soils.If the saturation degree increases,the ratio of the Rayleigh wave velocity to that of the shear wave and the real part of the velocity Rayleigh increase,while the normalized vertical and horizontal displacements of the soil skeleton and the fluid decrease;but when the saturation degree increases from 95% to 99% their amplitude changes are less than those when it increases from 99% to 100%.These conclusions provide a theoretical basis for study on propagation characteristics,in-situ testing and data analysis of Rayleigh waves.
出处
《振动与冲击》
EI
CSCD
北大核心
2008年第4期10-13,共4页
Journal of Vibration and Shock
关键词
准饱和土体
瑞利波
特征方程
饱和度
归一化位移
nearly saturated soils
Rayleigh wave
characteristic equation
saturation degree
normalized displacements
